Nitrogen

Abstract

Muskmelon seedlings (cv. Galia) were grown under hydroponic greenhouse conditions using 4 nutrient solutions containing 17 (N₁ and P₁) or 425 (N₂ and P₂) ppm of nitrogen and phosphorus. Four weeks after the beginning of nutrition, N‐stressed (N₁P₂) seedlings were transferred either to N₂P₁ or to N₂P₂ and P‐stressed (N₂P₁) seedlings were transferred either to N₁P₂ or to N₂P₂ for an additional growth period of 3 weeks. Repair of P‐stressed seedlings was faster than that of N‐stressed seedlings when both were transferred to N₂P₂. There was no difference in rate of seedling repair in N₂P₂ or N₂P₁ after N‐stress. In contrast, P‐stressed seedlings were repaired more rapidly under N₂P₂ than under N₁P₂. In N‐stressed seedlings new leaves appeared and the stem elongated at the beginning of repair. In repair of P‐stressed seedlings, existing old leaves first increased in size and then new leaves were produced. Dry weight/fresh weight ratios increased with seedling age and under nutrition stresses.

Key words:

• Nutritional deficiency
• growth analysis

Notes

Contribution No. 1752‐E, 1986 series, from the Agricultural Research Organization, Bet Dagan, Israel.